I need an iPhone file converter that works offline. Help me please.

Hello friends. I need an accessible iPhone app, an app that converts video to audio locally, meaning I want it to do the job entirely on the iOS device, without the need for an internet connection. Does this app exist? Everyone I meet converts online, which is not only inconvenient, but insecure.
If the application also converts text files, this will be an interesting differential. Help me please.
Thank you.

Forum: 

#1 Shortcuts

You can make a shortcut to do this using the shortcuts app built into your phone. Here is one that I created for this:
https://www.icloud.com/shortcuts/976c62b4cd484c678e1bab4e81239d4d
You will first have to go into your settings app, find shortcuts there and turn on the option to allow untrusted shortcuts, then you can click the link above to import it into your phone. When the shortcut is imported, it'll just show up as "video to audio" in the share sheet of any app IE photos. When you select it, it may take a moment for the conversion to complete. When it's done you'll get another share sheet, this time for the audio of the video. From there you can save it to the files app or send it to someone else or whatever else you may need.

Alternatively if you want to do this on your own, you can do the following (this is exactly how I made the shortcut above)

Create a new shortcut, and add in 2 actions. Encode media, where you need to set the audio only switch to on, followed by share. Then in the details screen which you can get to using the button at the top of the shortcut editing interface turn on the show in share sheet switch and configure the shorcut to only accept media. You can also give it a name here which you should probably do as that's how it'll come up in the share sheet.